126 bulletin: museum of comparative zoology. 



Ophiarachnella septemspinosa, 



Ophiarachna septemspinosa Miiller and Troschel, 1842. Sys. Ast., p. 105. 

 Pectinura septemspinosa Liitken, 1869. Add. Hist. Oph., 3, p. 33. 

 Pectinura rigida Lyman, 1874. Bull. M. C. Z., 3, p. '224. 



Ophiarachna armata Troschel, 1879. Sitzungsb. Niederli. Gesellsch. Bonn, p. 137. 

 Pectinura armata de Loriol, 1894. Mem. Soc. Phys. et Hist. Nat. Geneve, 32, pt. 1, 

 no. 3, p. 13. 



Moluccas ; Zanzibar : Mauritius ; Amboina ; Fiji Islands ; Ceylon ; off Borneo. 

 Littoral to 30 fins. 



The specimens in the M. C. Z. collection from Mauritius and Zanzibar, taken in 

 connection with Brock's (Zeit. f. w. Zool., 47, p. 472) and de Loriol's (1. c.) ex- 

 tended descriptions, and Doderlein's (Zool. Jahrb., Sys., 3, p. 830) notes,have satis- 

 fied me that Doderlein (Semon's Zool. Forsch., 5, p. 282) is correct in considering 

 0. armata too near 0. septemspinosa, that de Loriol is correct in regarding 

 0. rigida as very near 0. armata, and that Brock is entirely right in placing 0. 

 rigida as a synonym of 0. septemspinosa. -The three names undoubtedly belong 

 to a single species. Lyman's type of 0. rigida is a very large, unicolored speci- 

 men, but the arm-spines show the characteristic light tips. 



Ophiarachnella macracantha, sp. no v. 



(Greek paKpis = long + 'anavda = spine, in reference to the very long, lowest 

 arm-spine.) 



Disc 24 mm. in diameter, pentagonal, distinctly incised at base of each 

 arm ; arms about 125 mm. long, nearly 5 mm. wide, and 4 mm. high at base, 

 tapering gradually to the slender tip. Disc (except radial shields) covered with 

 a fairly coarse granulation, about 7 or 8 grains to a millimeter. Radial shields a 

 trifle longer than wide, about 1| mm. in diameter, very conspicuous. Upper 

 arm-plates about three times as wide as long with fairly straight margins and 

 rounded corners. Under arm-plates at first much wider than long, with very 

 convex distal margin and somewhat concave proximally ; further out they gradu- 

 ally become longer than wide. Pairs of pores are very noticeable between each 

 two plates of the first six or eight, and they apparently continue far beyond the 

 middle of the arm. Oral shields rounded with a very indistinct angle inwards, 

 usually wider than long, but one is longer than wide. Side mouth-shields very 

 small, bare. Supplementary oral plates, small and inconspicuous ; in one area 

 the supplementary plate is so small and so imperfectly separated from the oral 

 shield it might easily be overlooked. Oral papillae 10-12 on each mouth-angle, 

 flat, rounded, and well-spaced. Mouth-angle terminated by lowest tooth, which is 

 large, flat, and rounded. Arm-spines 8 or sometimes 9, upper and middle ones 

 as long as an arm-joint, somewhat pointed; next to lowest much longer than a 

 joint, bluntly pointed ; lowest long and conspicuous, equalling two joints, flat and 

 truncate. Tentacle-scales 2, about equally long and rounded at tip, but outer 

 much wider than inner. Color of disc and arms, above fawn-brown, beneath 



